How to design a questionnaire
A questionnaire is a measuring instrument, and a badly worded item measures the wrong thing just as surely as a miscalibrated scale. The goal: questions that every respondent reads the same way, answers honestly, and finishes. Two principles do most of the work — write neutral, single-idea questions, and keep it as short as the research questions allow.
Open vs closed questions
| Closed | Open | |
|---|---|---|
| Answer | Fixed options (scale, multiple choice) | Respondent’s own words |
| Data | Quick to analyse, comparable | Rich, but slow to code |
| Use for | Most items | A few targeted “why” questions |
Most surveys are mostly closed questions (often Likert scales) with a few open ones where you genuinely need the respondent’s own framing.
The wording mistakes that invalidate data
- Leading questions nudge toward an answer — “How helpful was our excellent service?” Strip the steer.
- Double-barrelled questions ask two things at once — “satisfied with price and quality?” Split them.
- Jargon & ambiguity mean two people answer different questions. Use plain, specific wording.
- Loaded or assuming questions — “How often do you skip class?” presumes they do.
Order, length, and piloting
Open with easy, engaging questions; put sensitive or demographic items near the end. Watch for order effects (an earlier question priming a later one). Above all, mind length: completion time drives drop-off, and a fatigued respondent gives careless answers. Cut any item that doesn’t map to a research question, then pilot the whole thing on a handful of people before launch — piloting catches confusing items nothing else will.
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Frequently asked questions
Open vs closed questions?
Closed have fixed options (quick to analyse); open are free text (richer, slower). Most surveys are mostly closed.
What is a leading question?
One that nudges toward an answer (“our excellent service”). It biases responses — keep wording neutral.
What is a double-barrelled question?
One that asks about two things at once (“price and quality”). Split it into two questions.
How long should it be?
As short as your research questions allow — length drives drop-off. Estimate completion time, cut, and pilot.